/**
 *    Copyright 2009-2015 the original author or authors.
 *
 *    Licensed under the Apache License, Version 2.0 (the "License");
 *    you may not use this file except in compliance with the License.
 *    You may obtain a copy of the License at
 *
 *       http://www.apache.org/licenses/LICENSE-2.0
 *
 *    Unless required by applicable law or agreed to in writing, software
 *    distributed under the License is distributed on an "AS IS" BASIS,
 *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *    See the License for the specific language governing permissions and
 *    limitations under the License.
 */
package org.apache.ibatis.type;

import java.sql.CallableStatement;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

import org.apache.ibatis.executor.result.ResultMapException;
import org.apache.ibatis.session.Configuration;

/**类型处理器的基类
 * 
 * @author Clinton Begin
 * @author Simone Tripodi
 */
public abstract class BaseTypeHandler<T> extends TypeReference<T> implements
		TypeHandler<T> {

	protected Configuration configuration;

	public void setConfiguration(Configuration c) {
		this.configuration = c;
	}

	@Override
	public void setParameter(PreparedStatement ps, int i, T parameter, JdbcType jdbcType) throws SQLException {
		// 特殊情况，设置NULL
		if (parameter == null) {
			if (jdbcType == null) {
				// 如果没设置jdbcType，报错啦
				throw new TypeException("JDBC requires that the JdbcType must be specified for all nullable parameters.");
			}
			try {
				// 设成NULL
				ps.setNull(i, jdbcType.TYPE_CODE);
			} catch (SQLException e) {
				throw new TypeException(
						"Error setting null for parameter #"
								+ i
								+ " with JdbcType "
								+ jdbcType
								+ " . "
								+ "Try setting a different JdbcType for this parameter or a different jdbcTypeForNull configuration property. "
								+ "Cause: " + e, e);
			}
		} else {
			try {
				// 非NULL情况，怎么设还得交给不同的子类完成, setNonNullParameter是一个抽象方法
				setNonNullParameter(ps, i, parameter, jdbcType);
			} catch (Exception e) {
				throw new TypeException(
						"Error setting non null for parameter #"
								+ i
								+ " with JdbcType "
								+ jdbcType
								+ " . "
								+ "Try setting a different JdbcType for this parameter or a different configuration property. "
								+ "Cause: " + e, e);
			}
		}
	}

	@Override
	public T getResult(ResultSet rs, String columnName) throws SQLException {
		T result;
		try {
			result = getNullableResult(rs, columnName);
		} catch (Exception e) {
			throw new ResultMapException("Error attempting to get column '" + columnName + "' from result set.  Cause: " + e, e);
		}
		if (rs.wasNull()) {
			return null;
		} else {
			return result;
		}
	}

	@Override
	public T getResult(ResultSet rs, int columnIndex) throws SQLException {
		T result;
		try {
			result = getNullableResult(rs, columnIndex);
		} catch (Exception e) {
			throw new ResultMapException("Error attempting to get column #" + columnIndex + " from result set.  Cause: " + e, e);
		}
		if (rs.wasNull()) {
			return null;
		} else {
			return result;
		}
	}

	@Override
	public T getResult(CallableStatement cs, int columnIndex) throws SQLException {
		T result;
		try {
			result = getNullableResult(cs, columnIndex);
		} catch (Exception e) {
			throw new ResultMapException("Error attempting to get column #" + columnIndex + " from callable statement.  Cause: " + e, e);
		}
		if (cs.wasNull()) {
			return null;
		} else {
			return result;
		}
	}

	public abstract void setNonNullParameter(PreparedStatement ps, int i, T parameter, JdbcType jdbcType) throws SQLException;

	public abstract T getNullableResult(ResultSet rs, String columnName) throws SQLException;

	public abstract T getNullableResult(ResultSet rs, int columnIndex) throws SQLException;

	public abstract T getNullableResult(CallableStatement cs, int columnIndex) throws SQLException;

}
